スコープ関数/kotlin

Scope functions don't introduce any new technical capabilities, but they can make your code more concise and readable.

スコープ関数の一覧

let

apply

run

also

with

どれもスコープを生成し、新しく変数を定義することなく処理を開始できる

使い分け

Executing a lambda on non-null objects: let

Introducing an expression as a variable in local scope: let

Object configuration: apply

Object configuration and computing the result: run

Running statements where an expression is required: non-extension run

Additional effects: also

Grouping function calls on an object: with

code:kotlin

val adam = Person("Adam").apply {

age = 20 // same as this.age = 20

city = "London"

}

println(adam)

これ初見で見たら絶対混乱するなぁ

文脈から予測はできる

慣れたらすごく直感的だけど